1. Field of the Invention
The present invention relates to a distribution container that is mounted in a liquid-discharging head of, for example, an ink-jet printer during transportation and storage to substitute for a liquid container containing liquid to be discharged, and to a distribution method for transporting and storing a liquid-discharging head with such a distribution container mounted therein. More particularly, the present invention relates to a technique of preventing air from flowing from a nozzle of a liquid-discharging head.
2. Description of the Related Art
Known ink-jet printers have a head including a plurality of nozzles arranged linearly (a type of liquid-discharging head). An ink cartridge (a type of liquid container) is mounted in the head, and ink in the ink cartridge is discharged from the head for printing. That is, substantially circular dots are formed on printing paper serving as a recording medium opposing an ink-discharging surface of the head by sequentially discharging ink from the nozzles onto the printing paper, thereby expressing images and characters by dots arranged vertically and horizontally.
FIG. 9 is a perspective view of a thermal head that performs thermal printing as an ink discharging method in which ink is discharged by thermal energy. As shown in FIG. 9, the thermal head includes ink chambers 12 filled with ink, and heating resistors 13 respectively provided in the ink chambers 12. When ink in each ink chamber 12 is rapidly heated by the heating resistor 13, a bubble is produced in the ink on the heating resistor 13, and the ink is discharged from a nozzle 18, as shown by the arrow, by the energy generated when the bubble is produced.
From the viewpoint of structure, heads are divided into a serial head that moves in the width direction of a recording medium for printing, and a line head including multiple head sections that are arranged in the width direction of a recording medium in accordance with the printing width.
FIG. 10A is a cross-sectional view of a line head in which an ink cartridge is mounted, and FIG. 10B is a cross-sectional view taken along line XB-XB in FIG. 10A.
In a line head 10 shown in FIGS. 10A and 10B, a nozzle sheet 17 having a plurality of equally spaced nozzles 18 is bonded to a head chip 19 having a plurality of heating resistors 13 arranged in one direction while a barrier layer 15 defining ink chambers 12 is provided therebetween. The nozzles 18 correspond to the ink chambers 12 and the heating resistors 13, respectively.
A common channel member 20 is provided on the head chip 19. An ink common channel 21 defined by the common channel member 20 communicates with all the ink chambers 12. The center of the common channel member 20 is connected to an ink cartridge 41 via an ink supply tube 23 having a valve device 22. The ink cartridge 41 also has a valve device 42.
Ink in the ink cartridge 41 is supplied to the common channel 21 through the valve devices 42 and 22, and fills the ink chambers 12. When the ink is discharged from the ink chambers 12, the inner pressure of the common channel 21 becomes negative, and valves in the valve devices 22 and 42 are pushed down. Consequently, the valve devices 22 and 42 are opened, and ink is supplied again from the ink cartridge 41 to the common channel 21, and fills the ink chambers 12 that have discharged the ink. Accordingly, when the ink cartridge 41 is mounted in the line head 10, the ink chambers 12 are constantly filled with ink.
Ink sometimes leaks from the nozzles 18 because of environmental factors, for example, vibrations during transportation of the ink-jet printer, and the storage temperature. When leakage occurs, the inner pressure of the common channel 21 becomes negative, and the valve device 22 is opened while the ink cartridge 41 is not mounted. Therefore, air flows into the common channel 21, and produces bubbles in the ink. If the bubbles enter the ink chambers 12, even when the heating resistors 13 are heated for printing, discharging failure occurs, for example, no ink is discharged or ink is insufficiently discharged. This reduces the printing quality.
Japanese Unexamined Patent Application Publication No. 2003-170606 discloses a technique of preventing ink leakage. In this technique, as shown in FIG. 10A, a protection sheet 24 is bonded to the nozzle sheet 17 having the nozzles 18 during transportation of the ink-jet printer so that ink does not leak from the nozzles 18 and air does not flow therein. During use, the protection sheet 24 is separated from the nozzle sheet 17 to expose all the nozzles 18.
In the above-described technique, however, when the protection sheet 24 is separated from the nozzle sheet 17, a force for vertically lifting the nozzle sheet 17 acts because of the adhesive force of the protection sheet 24. This may damage an ink-discharging surface of the nozzle sheet 17. Furthermore, since the separated protection sheet 24 remains adhesive, for example, when the finger or cloth of the user touches the protection sheet 24, it may be soiled with ink adhering to the adhesive surface of the protection sheet 24.
It is conceivable to solve the above problem by reducing the adhesive force of the protection sheet 24.
However, this method is not practical because the probability of ink leakage increases. Since the nozzle sheet 17 is large particularly in the line head 10, it is fundamentally difficult to bond the protection sheet 24 to the nozzle sheet 17 so that ink does not leak from all the nozzles 18. When the adhesive force is reduced in such a condition, reliability is seriously reduced.
In addition, it is difficult for the users themselves to bond the protection sheet 24 to cover all the nozzles 18, for example, during storage of the line head 10.
FIG. 11 is a cross-sectional view of a line head having a cap.
In a line head 10 shown in FIG. 11, an ink supply tube 23 is covered with a rubber cap 25, instead of using the protection sheet 24 shown in FIG. 10A. Therefore, even when a valve device 22 is opened, air does not flow from the ink supply tube 23.
In this line head 10, air is prevented from flowing from the ink supply tube 23 into a common channel 21 filled with ink, but flows from nozzles 18. That is, when ink leaks from any of the nozzles 18 and the inner pressure of the common channel 21 becomes negative, air flows from the other nozzles 18 because the ink supply tube 23 is covered with the cap 25. In particular, since the line head 10 has a large number of nozzles 18, ink leaks and air flows from multiple nozzles 18.